create table Person(
	id int identity(00,1), -- so tu dong tang
	Phone varchar(10)
) 
go
insert into Person(Phone)
values ('0909095445')
go
from Person

delete from Person where id=1; --mot so khi da xoa thi se bi xoa khoi he thong, khi so moi se tiep theo chu khong thay vao so da xoa
select * 